The remarkable and solemn title of Our Lady of the Rosary

It has always been the habit of Catholics in danger and in troublous times to fly for refuge to Mary, and to seek for peace in her maternal goodness; showing that the Catholic Church has always, and with justice, put all her hope and trust in the Mother of God. …

This devotion, so great and so confident, to the august Queen of Heaven, has never shone forth with such brilliancy as when the militant Church of God has seemed to be endangered by the violence of heresy spread abroad, or by an intolerable moral corruption, or by the attacks of powerful enemies. 

Ancient and modern history and the more sacred annals of the Church bear witness to public and private supplications addressed to the Mother of God, to the help she has granted in return, and to the peace and tranquility which she had obtained from God. Hence her illustrious titles of helper, consoler, mighty in war, victorious, and peace-giver.

And amongst these is specially to be commemorated that familiar title derived from the Rosary by which the signal benefits she has gained for the whole of Christendom have been solemnly perpetuated. 

Pope Leo XIII – excerpt of his encyclical letter Supremi Apostolatus Officio on the Rosary